Selph Liver & kidney

Kidney Function Blood Test

A 2-marker kidney function test using cystatin C to calculate eGFR, an alternative to creatinine-based kidney tests for people whose muscle mass or creatine use could affect a standard result.

  • Doctor reviewed
Sample
Blood
Collection
Venous draw (clinic, nurse visit or own kit)
Results in
5–6 days
Biomarkers
2
Doctor reviewed
Yes
Tests for
  • Estimated glomerular filtration rate (eGFR)
  • Cystatin C

Test specifications

Provider
Selph
Sample type
blood
Collection method
venous draw (clinic, nurse visit or own kit)
Turnaround time
5–6 days
Biomarkers tested
2
At-home test
No
Doctor reviewed
Yes
Gender focus
Both

What's tested

2 biomarkers as listed by Selph.

Kidney Function

  • Estimated glomerular filtration rate (eGFR)

Kidney health

  • Cystatin C

About this test

The Kidney Function Blood Test measures cystatin C and uses it to calculate your estimated glomerular filtration rate (eGFR), the standard measure of kidney function. Selph notes that cystatin C is not affected by muscle mass or creatine supplement use in the way that the more commonly used marker creatinine can be, which matters for people who train heavily or take creatine.

At £59, it costs about 56% less than the £135 median for the 20 similarly sized liver and kidney tests we track, and its 2 markers place it above the middle of that group on depth. There is no direct comparison group of equivalent cystatin C-based kidney tests in our data to benchmark it against more precisely.

value for money scores highly given how far below the broader market median it sits. Collection Convenience is the lowest of Selph's scoring criteria for this test, since it requires a venous draw at a clinic or with a nurse rather than an at-home finger-prick kit, and results take 5 to 6 days.

Who is it for?

This suits you if you want a kidney function result that is not skewed by high muscle mass or creatine use, for example if you train heavily, and you are comfortable arranging a venous blood draw. If those factors do not apply to you, a standard creatinine-based kidney or general health panel with a finger-prick option, such as Selph's 7 Simple Checks, may be more convenient.

How it works

This test requires a venous blood draw rather than a finger-prick; you can visit a partner clinic, book a nurse to draw blood at home or work, or arrange your own venous draw. A Selph doctor reviews your results and provides a written report, typically within 5 to 6 days.

Pros & cons

Pros

  • About 56% below the £135 median price for similarly sized liver and kidney tests we track.
  • Uses cystatin C, which is not affected by muscle mass or creatine use, unlike standard creatinine-based tests.
  • Results reviewed by a doctor within 5 to 6 days.

Cons

  • Requires a venous blood draw; there is no finger-prick option for this test.
  • Turnaround of 5 to 6 days is slower than Selph's finger-prick blood tests.

Our editorial score

Compare Health Test Score Cystatin C kidney test priced well below the broader market
Editorial confidence: 10.0/10

This kidney function test measures cystatin C and calculates eGFR from it for £59, about 56% below the £135 median for the 20 similarly sized liver and kidney tests we track. Using cystatin C rather than creatinine avoids a result being skewed by muscle mass or creatine supplementation. The main drawback is that it requires a venous blood draw rather than a simple finger-prick, and results take 5 to 6 days.

Score breakdown

  • Clarity and documentation 9.0/10

    The listing publishes a detailed description, the full biomarker list, a stated turnaround, clear collection options, the sample type; it does not state what the report looks like.

  • Clinical depth 7.9/10

    2 biomarkers, placing it in the 57th percentile of liver kidney tests we track.

  • Collection convenience 4.0/10

    Requires a venous draw at a clinic; a home nurse visit is offered; results in around 6 days, slower than similar tests.

  • Results and follow-up 7.0/10

    Results are reviewed by a doctor; the provider does not describe the report format.

  • Trust signals 10.0/10

    Trustpilot 4.9 from 71,592 reviews; accredited lab (UKAS ISO 15189 partner labs (Inuvi, TDL)); CQC registered; doctor review as standard.

  • Value for money 9.3/10

    £59.00 against a median of £135.00 for the 20 similarly sized liver kidney tests we track (-56%).

Calculated 13 September 2026 from the facts we hold about this test and provider, using our published scoring formula. Scores are not hand-edited.

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